updated for version 7.3.703

Problem:    When 'undofile' is reset the hash is computed unnecessarily.
Solution:   Only compute the hash when the option was set. (Christian Brabandt)

src/option.c

@@ -7572,6 +7572,11 @@ set_bool_option(opt_idx, varp, value, opt_flags)
 #ifdef FEAT_PERSISTENT_UNDO
     /* 'undofile' */
     else if ((int *)varp == &curbuf->b_p_udf || (int *)varp == &p_udf)
+    {
+	/* Only take action when the option was set. When reset we do not
+	 * delete the undo file, the option may be set again without making
+	 * any changes in between. */
+	if (curbuf->b_p_udf || p_udf)
 	{
 	    char_u	hash[UNDO_HASH_SIZE];
 	    buf_T	*save_curbuf = curbuf;
@@ -7579,9 +7584,9 @@ set_bool_option(opt_idx, varp, value, opt_flags)
 	    for (curbuf = firstbuf; curbuf != NULL; curbuf = curbuf->b_next)
 	    {
 		/* When 'undofile' is set globally: for every buffer, otherwise
-	     * only for the current buffer: Try to read in the undofile, if
+		 * only for the current buffer: Try to read in the undofile,
-	     * one exists and the buffer wasn't changed and the buffer was
+		 * if one exists, the buffer wasn't changed and the buffer was
-	     * loaded. */
+		 * loaded */
 		if ((curbuf == save_curbuf
 				|| (opt_flags & OPT_GLOBAL) || opt_flags == 0)
 			&& !curbufIsChanged() && curbuf->b_ml.ml_mfp != NULL)
@@ -7592,6 +7597,7 @@ set_bool_option(opt_idx, varp, value, opt_flags)
 	    }
 	    curbuf = save_curbuf;
 	}
+    }
 #endif
 
     /* 'list', 'number' */

src/version.c

@@ -719,6 +719,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    703,
 /**/
     702,
 /**/